Analogies aren't going to get any where because we could go all day with comparisons that prove our opinion.
An intro has a huge impression. Some are long, some are short, some don't even exist. How it is executed to the listener varies greatly. But, in most cases intros exist to build or create tension to something greater. And it's the producer's job to stay focused and make sure the listener will stay interested until the best parts.
Don't blame the audience for disliking the song. That doesn't mean the song is good or bad. However, It is always, always, always the producer or composer's fault. No matter what.